Bootstrap not working on rails 4 - ruby-on-rails

Question

I'm having problems with my app, I can't see any bootstraps effects on my rails app it looks the same. I have done bundle install, but I can't see any difference in it. This is my first time using bootstrap.
Here is my gem file:
source 'https://rubygems.org'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.5.1'
gem 'bootstrap-sass', '~> 3.3.6'
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.1.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby
# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '~> 0.4.0', group: :doc
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use Unicorn as the app server
# gem 'unicorn'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development
group :development, :test do
gem 'sqlite3'
# Call 'byebug' anywhere in the code to stop execution and get a debugger console
gem 'byebug'
end
group :development do
# Access an IRB console on exception pages or by using <%= console %> in views
gem 'web-console', '~> 2.0'
# Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
gem 'spring'
end
group :production do
gem 'pg'
gem 'rails_12factor'
And my application js:
// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or any plugin's vendor/assets/javascripts directory can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// compiled file.
//
// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
// about supported directives.
//
//= require jquery
//= require jquery_ujs
//= require bootstrap-sprockets
//= require turbolinks
//= require_tree .
And my application css:
/* This is a manifest file that'll be compiled into application.css, which will include all the files
* listed below.
*
* Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
* or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
*
* You're free to add application-wide styles to this file and they'll appear at the bottom of the
* compiled file so the styles you add here take precedence over styles defined in any styles
* defined in the other CSS/SCSS files in this directory. It is generally better to create a new
* file per style scope.
*
*= require_tree .
*= require_self
*/

Answer 1

You need to add the boostrap in your application.scss too.
Just follow the documentaion: https://github.com/twbs/bootstrap-sass#installation
#import "bootstrap-sprockets";
#import "bootstrap";
Note: rename your application.css to application.scss